MkDocs could gain at better exposing and documenting its API.

Some of it could help plugin/extension authors (reusing Markdown treeprocessors), but is not exposed. Some of it must be imported for integration within other Python tools, but is not exposed (entrypoints in __main__). Some of it is documented under API reference, some of it under Plugins, some of it is not documented.

Side note: One reason I started using MkDocs and writing mkdocstrings was to have all auto-documented objects (API autodoc) appear in the table of contents. But the default mkdocs theme does not allow that 😢

Relevant issues:

• API for running mkdocs #1240
• Allow seeing other pages' metadata when building a page #2743
• Enable users to change log level #2876 (careful with logging configuration in API vs CLI)
• Request: handle empty config items for plugins #3055
• ? (please comment and I'll add links)